1. Technical Field
The present invention relates to an optical position detection device capable of optically detecting the position of a target object in a detection area, and a display device with a position detection function provided with the optical position detection device.
2. Related Art
As the optical position detection device for optically detecting the position of the target object, there is proposed, for example, a device (see, e.g., JP-T-2003-534554 (Document 1; the term “JP-T” as used herein means a published Japanese translation of a PCT patent application)) of emitting detection light beams respectively from two light beam sources toward the target object via a transmissive member, and then receiving the component of the detection light beams, which are reflected by the target object and transmitted through the transmissive member, by a common light detector.
In the configuration described in Document 1 mentioned above, the position of the target object is detected based on the ratio between the emission intensities of the detection light beams when controlling the two light beam sources so that the reception intensity of the light detector in the case in which the detection light beam emitted from one of the two light beam sources is reflected by the target object and the reception intensity of the light detector in the case in which the detection light beam emitted from the other of the two light beam sources is reflected by the target object become equal to each other.
Here, the inventors study the optical position detection device capable of detecting the two-dimensional coordinate, and further the three-dimensional coordinate of the target object located in the detection area, and the configuration of the Document 1 uses a method of using the spatial relationship between the detection light beams respectively emitted from the two beam sources, and therefore has a problem that only the one-dimensional coordinate can be detected but detection of the two-dimensional coordinate is not achievable.